The document discusses the Lightweight Render Pipeline (LWRP) in Unity. It provides an overview of LWRP, including what it is, why developers should care about it, and how to set it up in a Unity project. It also describes the core rendering process in LWRP, including initializing camera data, culling, and executing render passes. Key aspects like shader constants, visible lights, and rendering data are explained.

1. GenerativeArt–MadewithUnity
Customizing a Production Pipeline
(Lightweight Render Pipeline)
Felipe Lira
Graphics Programmer
Unity Technologies
1
Note: If you are using a laptop download Unity 2018.2
and the following project: bit.ly/siggraph18

2. 2
Workshop Pre-requisites
●If you are on a SIGGRAPH computer
○ Start Unity and open SIGGRAPH2018-WORKSHOP
project in your Desktop
●If you are on your own computer
○ Download Unity 2018.2
○ Download the following project bit.ly/siggraph18
○ Start Unity and open the project you downloaded
●Slides: bit.ly/siggraph18_slides

3. 3
Workshop Agenda
●What is the Lightweight Render Pipeline (LWRP)
●Add LWRP to your project
●Convert a project to use LWRP
●Overview of LWRP rendering
●Customize LWRP renderer by adding custom passes
●Override LWRP renderer to implement a deferred renderer

4. 4
What is Lightweight Render Pipeline (LWRP)
●It’s a Scriptable Render Pipeline (SRP)
○ Rendering API exposed in C#
○ Open Source: https://github.com/Unity-Technologies/ScriptableRenderPipeline
●LWRP
○ Currently 1 of 2 of our inhouse Render Pipelines we are developing
○ Designed from the ground up to perform at best on mobile hardware
○ Modern APIs in mind, as well as Legacy APIs, eg GLES 2.0

5. 5
Why should you care about SRP and LWRP
●If you are
○ Student:
■ Learn Graphics Programming with a robust API
○ Game Developer:
■ Performance out of the box, explicit, lean and extensible
○ Researchers:
■ Implement, deploy and profile your research many platforms

6. 6

7. 7
Checkpoint!
●Open DemoScene
●You should see something like this

8. 8
How to get SRP and LWRP
●In this workshop you already have it!
○ The project you are using is bundled with LWRP for simplicity

9. 9
How to get SRP and LWRP
●You can also get it by creating a new project with LWRP
template

10. 10
How to get SRP and LWRP
●Or by downloading from package manager UI

11. 11
So now you have it!
● Let’s convert your project to use LWRP

12. 12
Checkpoint!
●Created LWRP asset
○ Assets -> Create -> Rendering -> Lightweight Pipeline Asset
●Assigned LWRP to Graphics Settings
○ Edit -> Project Settings -> Graphics Settings
○ Drag and Drop LWRP asset in SRP settings
●Upgraded materials to LWRP materials
○ Edit -> Render Pipeline -> Upgrade Project Materials …
●Checked rendering settings in LWRP asset
●You should have the same image as before converting

13. 13
Before coding let’s take a look at
core LWRP rendering

14. 14
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}

15. 15
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}
Called from C++ for:
● Scene
● Offscreen
● Editor
● Preview
● Reflection

16. 16
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}
Shader constants setup per
access frequency
● PerFrame
● PerCamera
● PerPass
● PerObject

17. 17
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}
Camera Related Rendering:
● HDR
● MSAA
● Shadows
● Render Scale
● PostProcessing
● Stereo Rendering

18. 18
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}
Visible:
● Renderers
● Lights
● ...

19. 19
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}
Data-drive rendering!
Rendering Data Based on:
● Cull Results
● Quality Settings
● Rendering Features
● Platform

20. 20
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}
● Setup render passes
○ Allocate Resources
○ Enqueue Render Passes
○ Configure pipeline state
● Can be overridden to your
own!

21. 21
public override void Render(ScriptableRenderContext context, Camera[] cameras)
{
SetupPerFrameShaderConstants();
foreach (Camera camera in cameras)
{
CameraData cameraData;
InitializeCameraData(camera, out cameraData);
SetupPerCameraShaderConstants(cameraData);
CullResults.Cull(cullingParameters, context, cullResults);
List<VisibleLight> visibleLights = cullResults.visibleLights;
RenderingData renderingData;
InitializeRenderingData(cameraData, visibleLights, out renderingData);
var setup = cameraData.camera.GetComponent<IRendererSetup>();
if (setup == null)
setup = defaultRendererSetup;
setup.Setup(renderer, context, cullResults, renderingData);
renderer.Execute(context, cullResults, renderingData);
context.Submit();
}
}
● Execute enqued passes
● Submit all queued rendering

22. 22
Let’s take a look at the
DefaultRendererSetup

23. 23
public void Setup(ScriptableRenderer renderer, … , RenderingData renderingData)
{
if (renderingData.shadowData.renderShadows)
renderer.Enqueue(m_ShadowPass);
bool requiresDepthPrepass = RequireDepthPrepass(renderingData.cameraData.requiresDepthTexture);
if (requiresDepthPrepass)
renderer.Enqueue(m_DepthPrepass);
renderer.Enqueue(m_SetupLightConstants);
renderer.Enqueue(m_RenderOpaquesForwardPass);
foreach (var pass in camera.GetComponents<IAfterOpaquePass>())
renderer.EnqueuePass(pass.GetPassToEnqueue(baseDescriptor, colorHandle, depthHandle));
if (camera.clearFlags == CameraClearFlags.Skybox)
renderer.Enqueue(m_RenderSkyboxPass);
renderer.Enqueue(m_RenderTransparentsPass);
if (renderingData.cameraData.postProcessEnabled)
renderer.Enqueue(m_PostProcessPass);
}

24. 24
public void Setup(ScriptableRenderer renderer, … , RenderingData renderingData)
{
if (renderingData.shadowData.renderShadows)
renderer.Enqueue(m_ShadowPass);
bool requiresDepthPrepass = RequireDepthPrepass(renderingData.cameraData.requiresDepthTexture);
if (requiresDepthPrepass)
renderer.Enqueue(m_DepthPrepass);
renderer.Enqueue(m_SetupLightConstants);
renderer.Enqueue(m_RenderOpaquesForwardPass);
foreach (var pass in camera.GetComponents<IAfterOpaquePass>())
renderer.EnqueuePass(pass.GetPassToEnqueue(baseDescriptor, colorHandle, depthHandle));
if (camera.clearFlags == CameraClearFlags.Skybox)
renderer.Enqueue(m_RenderSkyboxPass);
renderer.Enqueue(m_RenderTransparentsPass);
if (renderingData.cameraData.postProcessEnabled)
renderer.Enqueue(m_PostProcessPass);
}
● Enqueue render passes
based on received data
● ScriptableRenderPass is a
building block to a render
pipeline

25. 25
public void Setup(ScriptableRenderer renderer, … , RenderingData renderingData)
{
if (renderingData.shadowData.renderShadows)
renderer.Enqueue(m_ShadowPass);
bool requiresDepthPrepass = RequireDepthPrepass(renderingData.cameraData.requiresDepthTexture);
if (requiresDepthPrepass)
renderer.Enqueue(m_DepthPrepass);
renderer.Enqueue(m_SetupLightConstants);
renderer.Enqueue(m_RenderOpaquesForwardPass);
foreach (var pass in camera.GetComponents<IAfterOpaquePass>())
renderer.EnqueuePass(pass.GetPassToEnqueue(baseDescriptor, colorHandle, depthHandle));
if (camera.clearFlags == CameraClearFlags.Skybox)
renderer.Enqueue(m_RenderSkyboxPass);
renderer.Enqueue(m_RenderTransparentsPass);
if (renderingData.cameraData.postProcessEnabled)
renderer.Enqueue(m_PostProcessPass);
}
● Camera can contain scripts
that inject passes at specific
points in the pipeline
● IAfterOpaque is just one of
the many injecting points

26. 26
Quick Recap
●LWRP do every frame
1.Culling
2.Setup per frame and per camera data
3.IRendererSetup enqueue multiple ScriptableRenderPass
a.A custom ScriptableRenderPass can be added at many
hook points
b.The default renderer can be even completely overridden
4.Renderer execute all enqueued passes

27. 27
Adding a custom pass in LWRP
● Let’s switch to coding!
● We will:
○ Create a custom ScriptableRenderPass (MyNyanCatPass)
○ Inject the MyNyanCatPass after rendering opaques
(IAfterOpaque)

28. 28
Now it’s your time to code!
● What if I get lost?
○ Call for help!
○ Use AddPassAfterOpaqueCompleted.cs in your project as
reference

29. 29
Checkpoint
●You should have the following image

30. 30
Customizing the render pipeline
● How about we complete override the renderer now?!
● But first let’s review how to do a mobile deferred renderer

31. Tiled GPU rendering review
●Splits rendering into tiles
31
Textures Framebuffer
Main Memory
Fragment Shader Tile Memory
Geometry
Data
GPU

32. Tiled GPU rendering review
●Splits rendering into tiles
●For each tile
○ Tile LOAD Action
32
Textures
Main Memory
Geometry
Data
GPU
Fragment Shader Tile Memory
Framebuffer

33. Tiled GPU rendering review
●Splits rendering into tiles
●For each tile
○ Tile LOAD Action
○ Rendering
33
Textures
Main Memory
Geometry
Data
GPU
Fragment Shader Tile Memory
Framebuffer

34. Tiled GPU rendering review
●Splits rendering into tiles
●For each tile
○ Tile LOAD Action
○ Rendering
○ Tile STORE Action
34
Textures
Main Memory
Geometry
Data
GPU
Fragment Shader Tile Memory
Framebuffer

35. Tiled GPU rendering review
●Splits rendering into tiles
●For each tile
○ Tile LOAD Action
○ Rendering
○ Tile STORE Action
35
Textures
Main Memory
Geometry
Data
GPU
Fragment Shader Tile Memory
Framebuffer

36. Tiled GPU rendering review
●Splits rendering into tiles
●For each tile
○ Tile LOAD Action
○ Rendering
○ Tile STORE Action
36
Textures
Main Memory
Geometry
Data
GPU
Fragment Shader Tile Memory
Framebuffer

37. Traditional Deferred Rendering
●GBuffer pass
○ Allocate Images
○ Setup Framebuffer (MRT)
○ Render to MRT
○ Write tiles to main memory
Textures Framebuffer
Main Memory
GPU
Fragment Shader Tile Memory
Geometry
Data
Diffuse Specular +
Rougness
Normals LightAccum
(GI + Emissive)
Depth

38. Traditional Deferred Rendering
●Lighting pass
○ SetFramebuffer (LightAccum)
○ Load tiles from main memory
○ Read Input Textures from main memory
○ Render to LightAccumulation
○ Write tiles to main memory
Textures Framebuffer
Main Memory
GPU
Fragment Shader Tile Memory
Geometry
Data
Diffuse Specular Normals Light
Accumulation
Depth

39. 39
Rendering Efficiently on Mobile
●Minimize external memory read and writes
●Render Pass allows Tiled GPU interleaved rendering
○ Vulkan Multipass Mobile Deferred Done Right (Arntzen, GDC 2017)
Tile #0
Render GBuffer
Tile #0
Render Lighting
Tile #1
Render GBuffer
Tile #1
Render Lighting
Interleaved Rendering

40. 40
Rendering Efficiently on Mobile
●RenderPass API
○ Vulkan: Transient Buffers
○ Metal: Framebuffer Fetch
○ Emulated on all other rendering backends

41. 41
Mobile Deferred Renderer
● We will create a combined GBufferAndLighting renderpass
● For simplicity we will only support directional lights now
● It can easily be extended to support puntual lights
● Create an IRendererSetup
● Enqueue our render pass
● Add IRendererSetup to our camera

42. 42
Now it’s your time to code!
● What if I get lost?
○ Call for help!
○ Use MyDeferredRendererCompleted.cs in your project as
reference

43. 43
Before you leave!
1.Please rate this session in your SIGGRAPH app!
2.Save this link: bit.ly/siggraph18
3.We will have another awesome workshop on ShaderGraph!
a.Creating a Custom Production Ready Pipeline.
b.Same place, same hour!
4.We need to clear the booth for the next workshop.
5.Meet me outside for questions

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